Improving performance of RealTraps Mondo Bass Trap

I was originally going to purchase GIK Softfit Bass Traps because they had much better performance data compared to the RealTraps Mondo bass traps installed across a corner. However I was able to pick up some Mondo bass traps at a very good price. While I am pleased with the results of the Mondo panels I am wondering if I can improve their performance by filling the space behind the panel with some material. Would this improve the bass trapping performance? If so, what material is suggested?

Thank you.
Tboooe - Don't know Mondo and not sure what parameter you want to improve
but if it's additional sound absorption, check out a product called Roxul Safe 'n'
Thanks Ghosthouse. Given the size of my room I have a nasty bass resonance of 60hz. The GIK SOFTFIT product performs better at this freq than the Mondo traps (at least if I am understanding the data correctly).
Tboooe - visited the Mondo site. Not exactly sure which product of theirs you bought...those triangular traps? The Roxul is a dense but cuttable unfinished sound absorbing product. Can get it at Lowes. If there is room within the Mondo product you could maybe add the Roxul to give another layer of thickness. There is some acoustical info on the Roxul product in the PDF file here:
Ghosthouse I have the RealTraps Mondo Corner bass trap. I have it straddling the inward corner between two the intersection of two walls. Since the Mondo is straddling the corner there is plenty of space behind it.
I use a couple of Real Trap products (a Corner Mondo trap on a stand, and a Corner triangle trap underneath it on the floor). In that part of the room, I have no sound issues at all. Call real Traps at 866-732-5872. Jim was very helpful to me in selecting acoustic treatments for my listening room.
The ASC Tube Traps out performed the RealTraps Mondo Traps and the GIK Base Traps when each pair were straddling the front corners in my room. They are the real deal !
Samhar, the ASC tubes are indeed very nice but also much more expensive. I'm on a budget!ll
If budget is a concern you might look at these Cornerblox. Reasonably priced and should fit behind your traps. I ordered a set and delivery was prompt.
Thank you Timrhu. I just wish they publish some data. I'm trying the get better performance from 60hz and below.
They do have this on their web site. Although the lowest test frequency on the chart is 125Hz, the data does look pretty good for the price.

I attached some extra Auralex pieces to the front of mine for an extra couple inches of foam. From what I can tell the foam is identical to the Auralex foam. Both companies are located on the north of Indianapolis. It's obvious that the Cornerblox are cut from a 12x12 inch square piece. I'm thinking of asking if I can get an 8 foot long 12x12 inch square piece to stick in the corner.

I have no affiliation with this company, just use their stuff.